This invention relates to a control valve arrangement for an engine and more particularly to an improved control valve arrangement for an engine, a tuned induction system for an engine and an improved air inlet arrangement for an engine.
It is well known that, as with many other components of an internal combustion engine, the induction system is designed and tuned so as to provide optimum performance under certain running conditions. As such, optimum performance cannot be enjoyed under all running conditions. In order to broaden the range of optimum performance of an engine, it has been proposed to provide a dual or staged induction system for the engine having a relatively long inlet passage that serves the low speed running of the engine and a relatively short induction passage that serves the high speed running of the engine. A wide variety of such dual induction systems have been proposed.
For the most part, these dual induction systems employ a control valve arrangement for selecting whether the long or the short intake passages supply the engine during certain phases of running. Although these arrangements provide an improvement in the performance of the engine at least at the two ranges for which the induction passages are tuned, the torque curve of the engine is not as smooth as could be desired. For example, FIG. 1 of the drawings shows torque curve in broken lines for an engine constructed in accordance with a prior art type of construction. It should be noted that the torque curve has two components, the portion B1 and the portion B2. The portion B1 is the torque curve generated by the long low speed induction passage, while the curve B2 is that generated by the short high speed passage. Not only is there a dip in the point where these two curves cross but also the curves have a generally irregular configuration since the induction passage provides peak performance only at a relatively narrow range for which it was turned (The speeds R1 and R2).
It is, therefore, a principal object of this invention to provide an improved control valve arrangement for an engine that will improve the torque curves throughout the entire load speed range of the engine and not just for certain isolated speed conditions.
It is a further object of this invention to provide a control valve arrangement for an engine in which an effective torque curve is provided throughout the entire speed and load ranges with minimum dips in the curve.
In conjunction with the control valves for the induction system of the type previously described, it has been the conventional practice to use butterfly or pivoted type valves. These valves normally communicate the engine intake port with one of two different lengths intake passages. Since valve arrangements become quite complicated and add to the complexity of the induction system due to the use of two separate passages for each intake port of the engine.
It is, therefore, a still further object of this invention to provide an improved control valve arrangement for the induction system of an engine which permits the use variable length intake passages while simplifying the overall construction.
It is a further object of this invention to provide an improved slide type valve for a compound engine induction system that selectively changes the effective length of the system without requiring multiple parallel induction passages.
Although compound induction systems of the type described are effective in increasing the engine performance over a wider range of its running characteristics, these systems tend to become rather complex, as afore noted. These presents certain difficulties, particularly when the engine is positioned in the engine compartment of modern motor vehicle. It is, of course, desireable to provide a low hood line for the motor vehicles so as to improve streamlining, lessen wind resistance and improve economy. However, it is not always possible to do this with the prior art-type of induction systems due to their complexity.
It is, therefore, a further objection of this invention to provide an inlet device for the induction system of an engine which permits turning over wider ranges and nevertheless affords a compact construction.